This invention relates to an adsorption/absorption process for removing cyclopentadiene from a hydrocarbon stream containing both cyclopentadiene and dicyclopentadiene.
Dicyclopentadiene is formed as a by-product in various chemical processes, e.g., in the pyrolysis of ethane and higher alkanes to monoolefins (ethylene, propylene). The higher boiling fraction of this pyrolysis product contains aromatics, higher paraffins (pyrolysis gasoline), and cyclic diolefins, such as cyclopentadiene (CPD; C.sub.5 H.sub.6) and dicyclopentadiene (DCPD; C.sub.10 H.sub.12). When DCPD is separated by fractional distillation from other hydrocarbons present in this pyrolysis production fraction, small amounts of CPD are generally present as impurities in the DCPD stream. For some end-uses of DCPD (e.g., for making polyesters), the presence of CPD is detrimental. Thus, there is an ever present need to separate CPD from DCPD so as to obtain DCPD in sufficiently high purity for certain end-uses. The present invention is directed to an effective process for separating CPD from DCPD.